This is my first attempt of 'playing' with ferrite-cored ignition coil.
My initial intention is to improve the coil's responds to CDI output. According to my experience, iron-cored coil adds too much latency. Here's my attempt to 'fix' it...
Here's where I get my ferrite core, the infamous flyback transformer!
Here's the air-cored inductance. About 0.4mH.
Previous iron core shown left.
Unmodified stock ignition coil, about 7mH.
Side-by-side comparison between iron-core and ferrite-core.
Comparison of both stock and modded coils.
Ferrite-cored reading, about 8.4mH.
As obviously can be seen, swapping the iron-core to ferrite-core increases the inductance.
The performance haven't practically tested yet.